From: Steve French <stfrench@microsoft.com>
Date: Fri, 5 Jun 2020 17:19:46 -0500
Subject: [PATCH] smb3: extend fscache mount volume coherency check
Git-commit: 5865985416ebb5a0c198a819a098b5cc300ac8a4
Patch-mainline: v5.8-rc1
References: bsc#1192606

It is better to check volume id and creation time, not just
the root inode number to verify if the volume has changed
when remounting.

Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Acked-by: Enzo Matsumiya <ematsumiya@suse.de>
---
 fs/cifs/cache.c   |  9 ++-------
 fs/cifs/fscache.c | 17 +++++++++++++++--
 fs/cifs/fscache.h |  9 +++++++++
 3 files changed, 26 insertions(+), 9 deletions(-)

diff --git a/fs/cifs/cache.c b/fs/cifs/cache.c
index b7420e605b28..0f2adecb94f2 100644
--- a/fs/cifs/cache.c
+++ b/fs/cifs/cache.c
@@ -53,13 +53,6 @@ const struct fscache_cookie_def cifs_fscache_server_index_def = {
 	.type = FSCACHE_COOKIE_TYPE_INDEX,
 };
 
-/*
- * Auxiliary data attached to CIFS superblock within the cache
- */
-struct cifs_fscache_super_auxdata {
-	u64	resource_id;		/* unique server resource id */
-};
-
 char *extract_sharename(const char *treename)
 {
 	const char *src;
@@ -98,6 +91,8 @@ fscache_checkaux cifs_fscache_super_check_aux(void *cookie_netfs_data,
 
 	memset(&auxdata, 0, sizeof(auxdata));
 	auxdata.resource_id = tcon->resource_id;
+	auxdata.vol_create_time = tcon->vol_create_time;
+	auxdata.vol_serial_number = tcon->vol_serial_number;
 
 	if (memcmp(data, &auxdata, datalen) != 0)
 		return FSCACHE_CHECKAUX_OBSOLETE;
diff --git a/fs/cifs/fscache.c b/fs/cifs/fscache.c
index ea6ace9c2417..da688185403c 100644
--- a/fs/cifs/fscache.c
+++ b/fs/cifs/fscache.c
@@ -96,6 +96,7 @@ void cifs_fscache_get_super_cookie(struct cifs_tcon *tcon)
 {
 	struct TCP_Server_Info *server = tcon->ses->server;
 	char *sharename;
+	struct cifs_fscache_super_auxdata auxdata;
 
 	sharename = extract_sharename(tcon->treeName);
 	if (IS_ERR(sharename)) {
@@ -104,11 +105,16 @@ void cifs_fscache_get_super_cookie(struct cifs_tcon *tcon)
 		return;
 	}
 
+	memset(&auxdata, 0, sizeof(auxdata));
+	auxdata.resource_id = tcon->resource_id;
+	auxdata.vol_create_time = tcon->vol_create_time;
+	auxdata.vol_serial_number = tcon->vol_serial_number;
+
 	tcon->fscache =
 		fscache_acquire_cookie(server->fscache,
 				       &cifs_fscache_super_index_def,
 				       sharename, strlen(sharename),
-				       &tcon->resource_id, sizeof(tcon->resource_id),
+				       &auxdata, sizeof(auxdata),
 				       tcon, 0, true);
 	kfree(sharename);
 	cifs_dbg(FYI, "%s: (0x%p/0x%p)\n",
@@ -117,8 +123,15 @@ void cifs_fscache_get_super_cookie(struct cifs_tcon *tcon)
 
 void cifs_fscache_release_super_cookie(struct cifs_tcon *tcon)
 {
+	struct cifs_fscache_super_auxdata auxdata;
+
+	memset(&auxdata, 0, sizeof(auxdata));
+	auxdata.resource_id = tcon->resource_id;
+	auxdata.vol_create_time = tcon->vol_create_time;
+	auxdata.vol_serial_number = tcon->vol_serial_number;
+
 	cifs_dbg(FYI, "%s: (0x%p)\n", __func__, tcon->fscache);
-	fscache_relinquish_cookie(tcon->fscache, &tcon->resource_id, false);
+	fscache_relinquish_cookie(tcon->fscache, &auxdata, false);
 	tcon->fscache = NULL;
 }
 
diff --git a/fs/cifs/fscache.h b/fs/cifs/fscache.h
index 8c0862e41306..1091633d2adb 100644
--- a/fs/cifs/fscache.h
+++ b/fs/cifs/fscache.h
@@ -27,6 +27,15 @@
 
 #ifdef CONFIG_CIFS_FSCACHE
 
+/*
+ * Auxiliary data attached to CIFS superblock within the cache
+ */
+struct cifs_fscache_super_auxdata {
+	u64	resource_id;		/* unique server resource id */
+	__le64	vol_create_time;
+	u32	vol_serial_number;
+} __packed;
+
 /*
  * Auxiliary data attached to CIFS inode within the cache
  */
-- 
2.33.1